1. Field of the Invention
The present invention relates to a method for producing a cell analysis plate of the type comprising a thin layer of cells or a cell dispersion to be analysed provided on an analysis plate, the method comprising the following steps of:                taking a sample of a cell solution from a sample flask,        placing the sampled solution in a decantation chamber which is arranged above the analysis plate,        allowing the solution to decant in order to obtain the thin layer of cells on the analysis plate. The invention also relates to a device for producing a cell analysis plate allowing such a method to be carried out.        
2. Description of the Related Art
Cell analysis plates are produced, for example, in order to establish medical diagnoses. To that end, a deposit of cells is carried out on a glass slide.
A sample of the cells is taken by means of a sample brush, for example, by means of a smear, then the brush is arranged in a sample flask where the cells are placed in solution. A sample of a portion of the cell solution is then taken and placed in a decantation chamber located above the glass slide. After decantation and absorption of the cell admixture liquid, a thin layer of cells or cell dispersion is obtained on the glass slide and forms the analysis plate. Such a method is described, for example, in document FR-2792333.
It is desirable to obtain a thin layer or dispersion having constant cell density and in particular to have enough cells present to obtain a relevant diagnosis. In some applications, such as smears for screening for cancer of the cervix of the uterus, the number of cells must comply with the Bethesda classification which is a classification for standardising the diagnosis result of the smears, and each dispersion must thus comprise more than 5000 cells. Therefore, an adjustment of the number of cells sampled may be necessary if the density of the cells is not sufficient in the solution.
Currently, the measurement of the cell density is carried out on the cells present in the sample flask. That is to say that the sample is taken then placed in the flask, where it is dissolved and the density measurement is carried out in order to establish what quantity of cell suspension it is necessary to add to the cells on the analysis plate in order to have enough of them when the diagnostic reading is carried out. The density measurement is, for example, carried out by nephelometric analysis, that is to say, by measuring the diffraction of light which passes through the flask.
However, this type of measurement in the flask has a number of disadvantages. Firstly, the measurement is very unreliable because the sample brush present in the flask or the administrative label for identifying the flask that is adhesively bonded thereto can disrupt the measurement. On the other hand, the measuring method involves all the cell elements present in the flask, such as the epithelial cells, red blood corpuscles, inflammatory cells, etc., without distinction and does not allow selective measurement of the cells which are representative of and relevant to the diagnosis of the sample. Finally, if the quantity of cell suspension is adjusted directly during the sampling in the flask in order to obtain at once an analysis plate having optimum cell density, there is no complete automation for the procedure which remains open, nor any follow-up quality operation allowing a report to be produced setting out the low cell density of the solution initially present in the sample flask and allowing it to be corrected on the analysis plate by secondary enrichment.